Multifunction aircraft sensor probes are known, such as the multifunction aircraft probe assemblies disclosed in the above-cited Baltins et al '526 patent. In this regard, the probe assemblies of the Baltins et al '526 patent are generally embodied in a rotatable airstream direction probe which is additionally provided with a dynamic pressure sensing port positioned substantially midway between a pair of pneumatic sensing ports which are symmetrically positioned with respect to the probe's stagnation line. A set of pneumatic output ports may thus be provided, each of which communicates with a respective one of the pneumatic sensing ports in the probe.
Thus, when the pneumatic pressures within the paired sensing ports are balanced, the pneumatic pressure at the output port(s) in communication with the sensing ports will be essentially at a pressure P.sub.1 which is a monotonic function of static (atmospheric) pressure over a wide range of airspeeds (e.g., from 0.1 Mach to supersonic speeds). The dynamic pressure sensing port, on the other hand, will be presented directly to the airstream when the pressures within the pneumatic sensing ports are balanced. As a result, a dynamic pressure output port which communicates with the dynamic pressure sensing port will exhibit a maximum airstream pressure P.sub.0 which is a monotonic function of pitot (ram) pressure over a wide range of airspeeds. These pressures P.sub.1 and P.sub.0 can thus be converted mathematically into actual pitot (ram) and static (atmospheric) pressures undiluted by any error dependent upon the aircraft's angle of attack and/or side slip. The probe can thus be employed to derive angle of attack and/or side slip flight data information, in addition to primary flight data, such as airspeed, altitude and/or vertical speed.
It has now been discovered that the multifunction probe design embodied in the Baltins et al '526 patent may be improved by providing circumferentially separated pairs of sensing ports which are respectively dedicated to angle of attack functionality and air data pressure sensing functionality. The probe design in accordance with the present invention is especially well suited to reduce the impact of the complex shock system that develops about the probe during supersonic flight. Thus, improved airstream pressure sensing capabilities ensue.
In one aspect of the present invention, therefore, a multifunction aircraft probe is provided with a distal probe element which is adapted to project outwardly from an aircraft with which it is operatively mated and being mounted for rotational movement about its projection axis. The probe element is provided with a centrally located (i.e., in substantial alignment with the probe's stagnation line) dynamic pressure sensing port, and outer and inner pairs of pneumatic sensing ports which are symmetrically circumferentially separated from one another and from the dynamic pressure sensing port. Most preferably, each of the outer pneumatic sensing ports is circumferentially spaced from the central dynamic pressure sensing port by substantially 90.degree. (i.e., circumferentially separated from one another by about 180.degree. so as to be substantially latitudinally opposed to one another) while each of the inner pneumatic sensing ports is circumferentially spaced from the central dynamic pressure sensing port by substantially 45.degree. (i.e., circumferentially separated from one another by about 90.degree.. In such a manner, the angle of attack functionality may be maintained completely independent of the air data pressure sensing functionality of the probe assembly.
These and other aspects and advantages of the present invention will become more clear after careful consideration is given to the detailed description of the presently preferred exemplary embodiment thereof which follows.